Drugs for Cardiovascular Disease Flashcards
Lecture Outcomes
1) describe the basic features of the two broad categories of disorders affecting the
human cardiovascular system.
2) describe the main symptoms and pathobiological basis of angina.
3) describe the key historical events and circumstances surrounding the development
of nitroglycerin as an effective but flawed angina remedy.
4) describe the mechanisms underlying the anti-angina properties of nitroglycerin
5) explain the rationale for and clinical trial outcomes of mass prescription of
polypills containing multiple cardiovascular drugs in low and moderate income
countries.
6) explain the role of genetics in variable patient responses to cardiovascular
medicines and the potential clinical implications.
Aims of Lecture
1) To explore how discovering the
antianginal properties of nitroglycerin
inspired the development of many
drugs for cardiovascular disease.
2) To explore the role of genetics in
variable responses to cardiovascular
drugs.
Types of Cardiovascular Disease (CVD)
- CVDs due to atherosclerosis:
Ischaemic heart disease or coronary artery disease
(i.e., basis for “heart attacks”)
Cerebrovascular disease (i.e., basis for strokes)
Diseases of the aorta and arteries, including
hypertension and peripheral vascular disease. - Other CVDs
Congenital heart disease
Rheumatic heart disease
Cardiomyopathies
Cardiac arrhythmias
CVD in Australia – 2022 Snapshot (ABS Data)
5.2% or 1.3 million people had heart, stroke and vascular disease
↑ from 4.1% in 2001 but similar to 2007–08 (5.3%)
CVD slightly more common in males than females (5.9% c.f. 4.6%).
Prevalence strongly ↑ with age
Heaviest toll in low socioeconomic and regional populations
Angina – What is it?
Spasmodic bouts of intense discomfort in
upper chest
Pain often radiates to left arm
Sense of suffocation and impending death
Can be stable (predictable frequency,
provoked by exercise, excitement, etc) or
unstable (unpredictable without
provocation)
Can precede heart attack (“preinfarction’)
The Causes of Angina: Myocardial
Oxygen (O
2) Deprivation
Angina occurs when low blood flow (myocardial
ischemia) limits O2 delivery to heart muscle during
exertion
Atherosclerotic narrowing of coronary artery is main
cause (i.e. block in blood vessels which supply heart
muscle)
Involves fatty deposits (“plaques”) in blood vessel
(“atherosclerosis”)
Angina can reflect other causes (e.g. anaemia (low
haemoglobin), hypotension (low BP), endothelial
damage, etc)
1847: Ascanio Sobrero - Inventor of Nitroglycerin
Chemistry Professor in Turino, Italy
Face badly scarred in lab explosion
Invented nitroglycerin using glycerol and
mineral acids (needed to chill the reaction!)
Considered it too dangerous to be of
practical use
(“When I think of all the victims killed… I am
almost ashamed to admit to be its
discoverer.”)
Alfred Nobel Tames the Monster
1864, Nobel family company began selling
nitroglycerin to mining companies
‘64, explosion at Stockholm plant killed
Alfred’s brother (5 in total)
’66-’68, nitroglycerin kills scores of people
around the world
Alfred finds nitroglycerin is stable if
blended with porous silica gel
(“Dynamite” putty)
Invented patented detonator
which made him a massive
fortune
“Monday Disease” Afflicted 19th C Workers in TNT
Munitions Plants
Munitions factory workers exposed to large
quantities of nitroglycerin
Strong headaches & facial flushing on return
to work after weekend break
i.e., persistent vasodilatation during working week
Some workers solved situation by wearing
work clothes on weekend
Suggested that nitroglycerin residues in the
worker’s overalls were producing chronic
vasodilatation
1879 - Murrell’s First Human Trials
Tested nitroglycerin on 35 healthy
individuals
Considerable variability in response
“From a consideration of the
physiological action of the drug… I
concluded that it would probably prove
of service in the treatment of angina
pectoris, and I am happy to say this
expectation has been realised.”
Used early BP monitoring device to confirm
beneficial effects in 3 angina patients
William Murrell – 19th C Pioneer in Angina Treatment
Noted English doctor born in London in 1853
Trained in medicine alongside Sydney Ringer (notable
early pharmacologist)
1877, Physician at Westminster Hospital, London
Aware of conflicting literature reports concerning
nitroglycerin & headaches
Aware of use of amyl nitrate in angina by Lauder
Brunton
Wondered if nitroglycerin would be of value in angina
patients
Murrell’s Famous Self-Experiment
“I obtained some 1% solution. One afternoon, whilst
seeing out-patients, I remembered that I had a little
bottle in my pocket. Wishing to taste it, I applied the
moistened cork to my tongue, and a moment after, a
patient coming in, I had forgotten all about it.
“I had not asked my patient half a dozen questions before I felt a violent
pulsation in my head. The pulsation rapidly increased, and soon became
so severe that each beat of the heart seemed to shake my whole body.”
Nitroglycerin in Modern Medicine
Widely used to relieve angina pain in vulnerable
patients
Acts by dilating veins in periphery
“Preloading” decreases amount of blood
returned to heart
Peripheral “pooling” reduces effort needed by
ventricles to pump blood into circulation
Reduces workload on heart muscle (less severe
angina pain)
Other organic nitrates also used
Nitroglycerin is Taken Via Non-Oral Routes
Nonoral means pills are not swallowed (drug breaks down in stomach acid)
Used via various topical routes (oral cavity in acute attack)
Other routes: sticking patches (for skin application), oral sprays, oral pastes,
intradermal implants
Tablet, patches removed once pain subsides (avoid headaches)
Sublingual (under tongue)
Buccal (against cheek)
How Does Nitroglycerin Work?
Ongoing Challenges - 1: The Global Problem & Promise of Polypills
≈80% of global CVD in LMICs (Low + Middle Income Countries)
Low-income: <$1,005 GNI per capita
Lower-middle-income: $1,006 to $3,955 GNI
Less resources for public health
Growing interest in using polypills
Polypill = Fixed dose combinations of well tolerated (modest)
doses of several CV drugs, e.g.:
Statins to lower cholesterol
β-Blockers to reduce strength of heart beats
ACE Inhibitors to increase blood vessel diameters
Aspirin to lower risk of blood clotting
Given to everyone in population (e.g., > 55’s, etc) in hope of
↓ strokes & heart attacks
The PolyIran Study – Evidence for Polypill Effectiveness
Roshandel et al., 2019, first results from large population
polypill “cardioprotection” study
Randomised trial in NE Iran (Golestan Province)
6838 participants selected on basis of age (50–75 yrs)
Almost 90% had no previous CVD
Equal mix of male/females
The 4-drug polypill used contained:
2 half-dose blood pressure-lowering drugs
A moderate-intensity dose of a statin
Low-dose aspirin
Findings: ↓ ↓ in major CVD events over 5 yr
Adjusted hazard ratio [HR] was 0·66, 95% CI 0·55–0·80
Only 13% of participants discontinued the polypill
Suggests polypill approach is safe & effective
Ongoing Challenges – 2: Variability in Patient Response
Any two patients rarely respond identically to the same dose of a drug
This variability is obvious with cardiovascular drugs
i.e., “Mean” responses in populations can be misleading
Some patients gain little benefit, while others show exaggerated responses or toxicity
Holds true across many drug classes (e.g., statins, diuretics, anticoagulants)